I would be very interested in a USB to 1Wire Hub with 8 1 Wire ports. This would eb much better than using multiple DS9490R.
Chris On 22/04/2012 10:42, Patryk wrote: > I propose a new USB 1-wire adapter. > The DS2490 native USB 1-wire adapter is no longer in production. I think > you can still buy built adapters from Hobbyboards but if You want to build > your own it's nearly impossible to source this chip. The popular solution > is to use DS2480B with some serial to USB converter like FT232 it behaves > then like native DS2490. However if one plans to have w big 1-wire > network with multiple branches the better way seems be DS2482-800 which is > basically a 1-wire master with one bus connected to a 8 port hub. You can > have then a star topology. Again You can still(not sure) buy a hub from > Hobbyborad to achieve the same goal but the hub chip is also out of > production. So if you are familiar with soldering iron this is a solution > for you. > > The DS2482-800 uses I2C bus. The conversion form I2C to USB is handled by > Atmega8A which is a 8 bit microcontroller and runs a special program. > It's a very popular chip it costs about $2(at least in Poland). However > You have to upload the firmware to it for which you need a programmer. If > you don't have one but you have an old PC with parallel port you can build > one with few resistors and a plug. Also Raspberry Pi can program AVR chips. > First I run i2c-tiny-usb > http://www.harbaum.org/till/i2c_tiny_usb/index.shtml on Atmega8 > but there was a performance issue. The read from DS18B20 took about 3 > seconds > and without specifying the bus about 10. Compared to 1.5 with DS2480 and > similar > time connected to vga i2c port. > Fortunately there is a derivative project from Till's i2-usb-tiny it's > called OSFI(Open Source InterFace) . It's part of a project called > OpenServo http://www.openservo.com/StepByStep > It uses Atemga8 and has better performance because it uses some built in > i2c(do not know exactly). > > Here is the whole circuit. I think it's pretty explanatory. For testing > You can omit the voltage regulator and power it directly from USB and not > using the diodes should be fine for most computers. I done my prototype on > a breadboard and it works fine. > http://ubuntuone.com/6uM1yQRB36zgGEFDxrTc7c > > > On the 1-wire side DS9503 are not essential to get it running they just > protect the bus from electrostatic discharges. However they are cheap. I > used RJ-12 connectors (telephone) There are different standard's of wiring > the additional +5V the RJ45 are also popular. You can use screw connectors > as well. I think I will use 4 RJ45 for longer cables and if more power is > needed and RJ12 for thermometers. > > After assembling it on a breadboard You have to program the uC the > firmware can be downloaded from OpenServo cvs. > http://www.openservo.com/viewcvs/OpenServo/Interfaces/OpenServo_InterFace/driver/Version_2/firmware/?root=cvs > You need main.hex > avrdude -c usbasp -p atmega8 -U lfuse:w:0x9f:m -U hfuse:w:0xc9:m -U > flash:w:main.hex > > Then you can test if it's recognized by the system > lsusb shows > Bus 001 Device 005: ID 1964:0001 > There is no name for it > > Then you have to compile kernel module > http://www.openservo.com/viewcvs/OpenServo/Interfaces/OpenServo_InterFace/driver/Version_2/kernel/?root=cvs > make > sudo make install > sudo depmod -a > > sudo modprobe osif > > sudo modprobe i2c-dev > > then > sudo i2cdetect -l > should show something like this > i2c-0 i2c OSIF at bus 001 device 005 I2C adapter > > Then you can run owfs > sudo owfs –i2c=/dev/i2c-0 /mnt/owfs > You can also use the parameter > --i2c=ALL:ALL and owfs will look at every i2c device. However there is > some bug in older version an you might get segmentation fault. It is now > fixed in CVS > > The you should get something like this > sudo ls /mnt/owfs > bus.0 > bus.1 > bus.2 > bus.3 > bus.4 > bus.5 > bus.6 > bus.7 > settings > structure > uncached > statistics > system > > Here's the whole Eagle project the board is half done > http://ubuntuone.com/32tUJtqRyNr3ngTsApwW83 > and how it looks like on a breadboard > http://ubuntuone.com/0CUuACUSJMW69aK2FznM6i > > > Pleas give tips how to improve this tutorial. The board is on the way. > ------------------------------------------------------------------------------ For Developers, A Lot Can Happen In A Second. Boundary is the first to Know...and Tell You. Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! http://p.sf.net/sfu/Boundary-d2dvs2 _______________________________________________ Owfs-developers mailing list Owfs-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/owfs-developers
